Earthworms

An earthworm moving through its tunnelEarthworms are long, thin, soft-bodied invertebrates with no legs, eyes or ears that live in the soil. They are a kind of segmented worm: worms whose bodies are divided into ring-like segments. The group also includes leeches and ragworms. Many segmented worms live in the sea. The earthworm's basic shape is a tube, divided into segments, called annuli, that divide the body into different compartments. In adults there is a belt-like swelling around some of the central segments. Known as the clitellum, this is where its eggs are stored.

Eating and breathing

The digestive system runs straight through its body from the mouth at one end to the anus at the other. An earthworm can eat up to one third of its body weight in soil and dead plant material in a single day. The worm breathes in oxygen through its skin.

Movement

Except for the front and rear ones, each segment is covered with bristle-like hairs, called setae. An earthworm moves through the soil by using muscles to shorten its body, anchor itself to the surrounding soil with its setae, then lengthen its body to haul itself along. It produces a slimy mucus to moisten its body and make the passage through the soil easier.